The technology of the present disclosure relates generally to an optical fiber-based distributed antenna system (DAS), and more particularly to a flexible head-end chassis that includes a plurality of module slots each configured to flexibly receive either a radio interface module (RIM) or an optical interface module (OIM), and provide automatic identification and interconnection of the received RIM or OIM in the optical-fiber based DAS.
Wireless communication is rapidly growing, with ever-increasing demands for high-speed mobile data communication. As an example, local area wireless services (e.g., so-called “wireless fidelity” or “WiFi” systems) and wide area wireless services are being deployed in many different types of areas (e.g., coffee shops, airports, libraries, etc.). Distributed communications or antenna systems communicate with wireless devices called “clients,” “client devices,” or “wireless client devices,” which must reside within the wireless range or “cell coverage area” in order to communicate with an access point device. Distributed antenna systems are particularly useful to be deployed inside buildings or other indoor environments where client devices may not otherwise be able to effectively receive radio-frequency (RF) signals from a source, such as a base station for example. Example applications where distributed antenna systems can be used to provide or enhance coverage for wireless services include public safety, cellular telephony, wireless local access networks (LANs), location tracking, and medical telemetry inside buildings and over campuses.
One approach to deploying a distributed antenna system involves the use of RF antenna coverage areas, also referred to as “antenna coverage areas.” Antenna coverage areas can be formed by remotely distributed antenna units, also referred to as remote units (RUs). The remote units each contain or are configured to couple to one or more antennas configured to support the desired frequency(ies) to provide the antenna coverage areas. Antenna coverage areas can have a radius in the range from a few meters up to twenty meters as an example. Combining a number of remote units creates an array of antenna coverage areas. Because the antenna coverage areas each cover small areas, there typically may be only a few users (clients) per antenna coverage area. This arrangement generates a uniform high quality signal enabling high throughput supporting the required capacity for the wireless system users.
As an example, FIG. 1 illustrates distribution of communications services to coverage areas 10(1)-10(N) of a DAS 12, wherein ‘N’ is the number of coverage areas. These communications services can include cellular services, wireless services such as RFID tracking, Wireless Fidelity (WiFi), local area network (LAN), WLAN, and combinations thereof, as examples. The coverage areas 10(1)-10(N) may be remotely located. In this regard, the remote coverage areas 10(1)-10(N) are created by and centered on remote antenna units 14(1)-14(N) connected to a central unit 16 (e.g., a head-end controller or head-end unit). The central unit 16 may be communicatively coupled to a base station 18. If the DAS 12 is a broadband DAS, the central unit 16 receives downlink communications signals 20D in multiple frequency bands for different communications services from the base station 18 to be distributed to the remote antenna units 14(1)-14(N). The remote antenna units 14(1)-14(N) are configured to receive downlink communications signals 20D from the central unit 16 over a communications medium 22 to be distributed as downlink communications signals 20D to the respective coverage areas 10(1)-10(N) of the remote antenna units 14(1)-14(N). Each remote antenna unit 14(1)-14(N) may include an RF transmitter/receiver (not shown) and a respective antenna 24(1)-24(N) operably connected to the RF transmitter/receiver to wirelessly distribute the downlink communications signals 20D to client devices 26 within their respective coverage areas 10(1)-10(N). The remote antenna units 14(1)-14(N) in the DAS 12 are also configured to receive uplink communications signals 20U in multiple frequency bands from the client devices 26 in their respective coverage areas 10(1)-10(N). The uplink communications signals 20U can be filtered, amplified, and/or combined together into the combined uplink communications signals 20U to be distributed to the central unit 16, and separated into respective bands to distribute to the base station 18.
Optical fiber can also be employed in the DAS 12 in FIG. 1 to communicatively couple the central unit 16 to the remote antenna units 14(1)-14(N) for distribution of the downlink communications signals 20D and the uplink communications signals 20U. Benefits of optical fibers include extremely wide bandwidth and low noise operation. In this regard, FIG. 2 is a schematic diagram of an exemplary optical fiber-based DAS 30 (hereinafter “DAS 30”). The DAS 30 in this example is comprised of three (3) main components. One or more radio interfaces provided in the form of radio interface modules (RIMs) 32(1)-32(M) are provided in a central unit 34 to receive and process received electrical downlink communications signals 36D(1)-36D(R) prior to optical conversion into optical downlink communications signals. The notations “1-R” and “1-M” indicate that any number of the referenced component, 1-R and 1-M, respectively, may be provided. Each RIM 32(1)-32(M) can be designed to support a particular type of radio source or range of radio sources (i.e., frequencies) to provide flexibility in configuring the central unit 34 and the DAS 30 to support the desired radio sources. The electrical downlink communications signals 36D(1)-36D(R) are provided from the RIMs 32(1)-32(M) to a plurality of optical interfaces provided in the form of optical interface modules (OIMs) 38(1)-38(N). The OIMs 38(1)-38(N) each include electrical-to-optical (E/O) converters (not shown) to convert the electrical downlink communications signals 36D(1)-36D(R) into the downlink optical communications signals 40D(1)-40D(R). The optical downlink communications signals 40D(1)-40D(R) are communicated over optical downlink fiber communications medium 42D to a plurality of remote units 44(1)-44(S), which may be remote antenna units. The notation “1-S” indicates that any number of the referenced component, 1-S, may be provided. Optical-to-electrical (O/E) converters (not shown) provided in the remote units 44(1)-44(S) convert the optical downlink communications signals 40D(1)-40D(R) back into the electrical downlink communications signals 36D(1)-36D(R), which are provided to antennas 48(1)-48(S) in the remote units 44(1)-44(S) to client devices (not shown) in the reception range of the antennas 48(1)-48(S).
With continuing reference to FIG. 2, E/O converters (not shown) are also provided in the remote units 44(1)-44(S) to convert received electrical uplink communications signals 50U(1)-50U(S) received from client devices (not shown) through the antennas 48(1)-48(S) into optical uplink communications signals 40U(1)-40U(S). The remote units 44(1)-44(S) communicate the optical uplink communications signals 40U(1)-40U(S) over an uplink optical fiber communications medium 42U to the OIMs 38(1)-38(N) in the central unit 34. The OIMs 38(1)-38(N) include O/E converters (not shown) that convert the received uplink optical communications signals 40U(1)-40U(S) into electrical uplink communications signals 52U(1)-52U(S), which are processed by the RIMs 32(1)-32(M) and provided as electrical uplink communications signals 52U(1)-52U(S). The central unit 34 may provide the electrical uplink communications signals 52U(1)-52U(S) to a base station or other communications system.
With continuing reference to FIG. 2, the central unit 34 includes a dedicated RIM chassis 54 configured to house and support the RIMs 32(1)-32(M) and a dedicated OIM chassis 56 to house and support the OIMs 38(1)-38(N) as modular components. For example, the RIMs 32(1)-32(M) may be provided as circuit board cards that can be installed in circuit board card slots in the RIM chassis 54. When the RIMs 32(1)-32(M) are fully inserted in the RIM chassis 54, the RIMs 32(1)-32(M) connect to a backplane that provides interconnectivity within the optical fiber-based DAS 30. The OIMs 38(1)-38(N) may also be provided as circuit board cards that can be installed in circuit board card slots in the OIM chassis 56. When the OIMs 38(1)-38(N) are fully inserted in the OIM chassis 56, the OIMs 38(1)-38(N) connect to a backplane that provides interconnectivity within the optical fiber-based DAS 30. The number of RIMs 32(1)-32(M) provided in the central unit 34 is based on the number of communications services and/or remote units to be supported in the optical fiber-based DAS 30. The number of OIMs 38(1)-38(M) provided in the central unit 34 is based on the number of remote units 44(1)-44(S) supported by the optical fiber-based DAS 30. It may be desired to change the configuration of the optical fiber-based DAS 30 such that more RIMs 32(1)-32(M) or OIMs 38(1)-38(N) need to be provided in the central unit 34. However, if the RIM chassis 54 or OIM chassis 56 is full, it is not possible to install additional RIMs 32(1)-32(M) or OIMs 38(1)-38(N), respectively, without reconfiguring the optical fiber-based DAS 30, such as by providing additional chassis.
No admission is made that any reference cited herein constitutes prior art. Applicant expressly reserves the right to challenge the accuracy and pertinency of any cited documents.